The invention claimed herein was made by or behalf of Universite de Srasbourg, Le Center national De La Recherche Scientifique, and NexGenix Pharmaceuticals Inc., who are parties to a joint research agreement signed on Jul. 1, 2007 and related to marcrolcyclic compounds, such as radicicol and its derivatives, which are useful as kinase and HSP90 inhibitors.
In the mid-1950's, it was discovered that phosphorylation can reversibly alter the function of enzymes by means of protein kinases which catalyze phosphorylation, or by protein phosphatases which are involved in the dephosphorylation step. These reactions play an essential role in regulating many cellular processes, especially signaling transduction pathways. In the late 1970's, the Rous sarcoma virus (v-Src)'s transforming factor was discovered to be a protein kinase, and also tumor-promoting phorbol esters were found to be potent activators of protein kinase C, revealing the first known connection between disease and abnormal protein phosphorylation. Since then transduction mechanistic defects have been found to cause numerous oncogenic processes and to have a role in diabetes, inflammatory disorders, and cardiovascular diseases. (T. Hunter, Cell, 100:113-127 (2000); P. Cohen, Nat. Rev. Drug Discov., 1:309 (2002)). Thus selective kinase and phosphatase inhibitors have emerged as important drug targets, and inhibition of kinase phosphorylation activity is one of the most promising strategies for chemotherapy.
Macrocyclic resorcylic acid lactones such as radicicol and the related pochonins, are a structurally related group of secondary metabolites isolated from cultures of the clavicipitaceous hyphomycete Pochonia genus, such as Pochonia chlamydosporia var. catenulate strain P0297. See, e.g., V. Hellwig et al., J. Natural Prod., 66(6):829-837 (2003). These compounds and analogs or derivatives of the compounds have been evaluated as kinase inhibitors or inhibitors of HSP90. Halohydrin and oxime derivatives of radicicol were prepared and evaluated for their v-src tyrosine kinase inhibitory, antiproliferative, and antitumor in vitro activity (T. Agatsuma et al., Bioorg. & Med. Chem., 10(11):3445-3454 (2002).
Like kinases, heat shock proteins (HSPs) interact with ATP and are important targets for controlling disease, however they have a different mechanistic effect. Immediately after exposure to a stress such as heat, hypoxia or acidosis, cells in most tissues rapidly escalate production rate of the HSPs. It is now believed that heat HSPs are molecular chaperones, i.e., they prevent improper associations and assist in the correct folding of other cellular proteins collectively termed clients and substrates. HSP's are also found in association with tumors and other pathophysiological conditions. In fact, chaperone proteins facilitate the survival of tumor cells in stressful environments by facilitating tolerance of alterations inside the cell. HSPs are ubiquitous, highly conserved among the species, and usually classified by molecular weight to the following major families: HSP100, HSP90, HSP70, HSP60 and small HSPs. These families have structural and functional differences, but work cooperatively at different stages of protein folding. HSP90 has attracted particular attention due to its association with many types of signaling molecules such as v-Src and Raf that play a critical role in malignant transformation and metastasis development. Thus, HSP90 inhibitors are desired for designing chemotherapies, and also for elucidating the interplay in complex signaling networks.
Heat Shock Protein 90's (Hsp90s) are ubiquitous chaperone proteins that maintain the proper conformation of many “client” proteins (see Kamal et. al. Trends Mol. Med. 2004, 10, 283-290; Dymock et. al. Expert Opin. Ther. Patents 2004, 14, 837-847; Isaacs et. al. Cancer Cell, 2003, 3, 213; Maloney et. al. Expert Opin. Biol. Ther. 2002, 2, 3-24 and Richter et. al. J. Cell. Physiol. 2001, 188, 281-290), and are involved in folding, activation and assembly of a wide range of proteins, including key proteins involved in signal transduction, cell cycle control and transcriptional regulation. Researchers have reported that HSP90 chaperone proteins are associated with important signaling proteins, such as steroid hormone receptors and protein kinases, including, e.g., Raf-1, EGFR, v-Src family kinases, Cdk4, and ErbB-2 (Buchner, TIBS, 1999, 24, 136-141; Stepanova et. al., Genes Dev. 1996, 10, 1491-502; Dai et. al., J. Biol. Chem. 1996, 271, 22030-4). Studies further indicate that certain co-chaperones, e.g., Hsp70, p60/Hop/Sti1, Hip, Bag1, HSP40/Hdj2/Hsj1, immunophilins, p23, and p50, may assist HSP90 in its function (see for example Caplan, Trends in Cell Biol., 1999, 9, 262-268). Inhibition of Hsp90 causes these client proteins to adopt aberrant conformations, and these abnormally folded proteins are rapidly eliminated by the cell via ubiquitinylation and proteasome degradation. Interestingly, the list of Hsp90 client proteins includes a series of notorious oncogenes. Four of them are clinically validated cancer targets: HER-2/neu (Herceptin® (trastuzumab)), Bcr-Abl (Gleevec® (imatinib mesylate)), the estrogen receptor (tamoxifen), and the androgen receptor (Casodex® (bicalutamide)), while the others play a critical role in the development of cancer. Some of the most sensitive Hsp90 clients are involved in growth signaling (Raf-1, Akt, cdk4, Src, Bcr-Abl, etc). In contrast, few tumor suppressor genes, if any, seem to be clients of Hsp90 (for lists of client proteins see Pratt et. al. Exp. Biol. Med. 2003, 228, 111-133; Workman et. al. Cancer Lett. 2004, 206, 149-157 and Zhang et. al. J. Mol. Med. 2004, 82, 488-499), and consequently, inhibition of Hsp90 has an overall anti-proliferative effect. In addition, some client proteins are involved in other fundamental processes of tumorigenesis, namely apoptosis evasion (e.g. Apaf-1, RIP, Akt), immortality (e.g. hTert), angiogenesis (e.g. VEGFR, Flt-3, FAK, HIF-1), and metastasis (c-Met).
The numerous client proteins of HSP90 play a crucial role in growth control, cell survival and development processes, and those clients are known to include receptor tyrosine kinases, serine/threonine kinases, steroid hormone receptors, transcription factors and telomerase.
In addition to anti-cancer and antitumorgenic activity, HSP90 inhibitors have also been implicated in a wide variety of other utilities, including use as anti-inflammation agents, anti-infectious disease agents, agents for treating autoimmunity, agents for treating ischemia, and agents useful in treating neurodegenerative diseases and in promoting nerve regeneration (see M. Waza et al, Nature Med. 11:1088 (2005); Rosen et al., WO 02/09696; PCT/US01/23640; Degranco et al., WO 99/51223; PCT/US99/07242; Gold, U.S. Pat. No. 6,210,974 B1). There are reports in the literature that fibrogenetic disorders including but not limited to scleroderma, polymyositis, systemic lupus, rheumatoid arthritis, liver cirrhosis, keloid formation, interstitial nephritis, and pulmonary fibrosis may be treatable. (Strehlow, WO 02/02123; PCT/US01/20578).
Some resorcylic acid lactones have been found to inhibit HSP90, thus natural products radicicol and geldanamycin (P. Delmotte and J. Delmotte-Plaquee, Nature (London), 171:344 (1953); and C. DeBoer et al., J Antibiot (Tokyo), 23:442 (1970), respectively) were shown to suppress the transformed phenotype of cell expressing activated Src (H. J. Kwon et al., Cancer Research, 52:6926 (1992); Y. Uehara et al., Virology, 164:294 (1988)). Related compounds such as herbimycin have been reported to have similar effects (S. Omura et al., J Antibiot (Tokyo), 32:255 (1979).

Other resorcylic acid lactones (RALs) studied in this respect include 17-allylamino-17-demethoxygeldanamycin (17AAG) (D. B. Solit et al., Clin. Cancer Res., 8:986 (2002); L. R. Kelland et al., J. Natl. Cancer Inst., 91:1940 (1999)); 17DMAG (J. L. Eiseman et al., Cancer Chemother. Pharmacol., 55:21-32 (2005)); IPI-504 (J. Ge et al., J. Med. Chem., 49:4606 (2006); oxime derivatives such as KF25706 (S. Soga, et al., Cancer Res., 59:2931 (1999)) and KF55823 (S. Soga et al., Cancer Chemotherapy and Pharmacology, 48:435 (2001)); and Danishefsky et al.'s cycloproparadicicol (A. Rivkin et al., Ibid., 44:2838 (2005)). Structurally related variants include chimeric inhibitors having radicicol's carboxyresorcinol and the geldanamycin's benzoquinone (R. C. Clevenger and B. S. Blagg, Org. Lett., 6:4459 (2004); G. Shen and B. S. Blagg, Ibid. 7:2157 (2004); G. Shen et al., J. Org. Chem., 71:7618 (2006)).
